remove unused imports (closes #12432)

A patch from Vincent Legoll.
diff --git a/Lib/glob.py b/Lib/glob.py
index 36d493d..c5f5f69 100644
--- a/Lib/glob.py
+++ b/Lib/glob.py
@@ -1,5 +1,6 @@
 """Filename globbing utility."""
 
+import sys
 import os
 import re
 import fnmatch